Guide wire

ABSTRACT

A guide wire includes a wire member having a first wire disposed on the distal side of the guide wire, and a second wire disposed on the proximal side from the first wire. The second wire is made from a material having an elastic modulus larger than that of the first wire. For example, the first wire is made from a superelastic alloy, and the second wire is made from a stainless steel. The first wire is joined to the second wire at a welded portion by welding. A coil is disposed on the distal side from the first wire. A cover layer is formed on the outer peripheral surface of the wire member in such a manner as to cover at least the welded portion. The cover layer is made from a material capable of reducing the friction of the cover layer, for example, a fluorocarbon resin or a hydrophilic material, to thereby improve the sliding performance of the guide wire. Such a guide wire is excellent in operationality and kink resistance.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a guide wire, particularly to aguide wire used to guide a catheter in a body lumen such as a bloodvessel.

[0003] 2. Description of the Related Art

[0004] Guide wires are used to guide a catheter in treatment of cites atwhich open surgeries are difficult or which require minimallyinvasiveness to the body, for example, PTCA (Percutaneous TransluminalCoronary Angioplasty), or in examination such as cardio-angiography. Aguide wire used in the PTCA procedure is inserted, with the distal endprojecting from the distal end of a balloon catheter, into the vicinityof a target angiostenosis portion together with the balloon catheter,and is operated to guide the distal end portion of the balloon catheterto the target angiostenosis portion.

[0005] A guide wire used to insert a catheter into a blood vesselcomplicatedly bent requires appropriate flexibility and restoringperformance against bending, pushability and torque transmissionperformance (generically called “operationality”) for transmitting anoperational force from the proximal end portion to the distal side, andkink resistance (often called “resistance against sharp bending”). Toobtain appropriate flexibility as one of the above-describedperformances, there has been known a guide wire configured such that ametal coil having flexibility is provided around a small-sized coremember at the distal end of the guide wire, or a guide wire including acore member made from a superelastic material such as an Ni—Ti alloy forimproving the flexibility and restoring performance.

[0006] Conventional guide wires include a core member that issubstantially made from a single material. In particular, to enhance theoperationality of the guide wire, a material having a relatively highelastic modulus is used as the material of the core member. The guidewire including such a core member, however, has an inconvenience thatthe distal end portion of the guide wire becomes lower in flexibility.On the other hand, if a material having a relatively low elastic modulusis used as the material of the core member for increasing theflexibility of the distal end portion of the guide wire, theoperationality of the proximal end portion of the guide wire isdegraded. In this way, it has been regarded as difficult to satisfy bothrequirements associated with the flexibility and operationality by usinga core member made from a single material.

[0007] A guide wire intended to solve such a problem has been disclosed,for example, in U.S. Pat. No. 5,171,383, wherein a Ni—Ti alloy wire isused as a core member, and the distal side and the proximal side of thealloy wire are heat-treated under different conditions in order toenhance the flexibility of the distal end portion of the alloy wirewhile enhancing the rigidity of the proximal side of the alloy wire.Such a guide wire, however, has a problem that the control of theflexibility of the distal end portion by heat-treatment has alimitation. For example, even if it is successful to obtain a sufficientflexibility of the distal end portion of the alloy wire, it may oftenfail to obtain a sufficient rigidity on the proximal side of the alloywire.

SUMMARY OF THE INVENTION

[0008] An object of the present invention is to provide a guide wireexcellent in operationality and kink resistance.

[0009] To achieve the above object, according to a first aspect of thepresent invention, there is provided a guide wire including a wiremember including a welded portion formed by welding a first wiredisposed on the distal side of the wire body to a second wire disposedon the proximal side from the first wire and made from a material havingan elastic modulus larger than that of the first wire, the weldedportion being made substantially smooth, and a cover layer provided onthe outer periphery of the wire body covering at least the weldedportion between the first wire and the second wire.

[0010] According to a second aspect of the present invention, there isprovided a guide wire including a wire member including a welded portionformed by welding a first wire disposed on the distal side of the wiremember to a second wire disposed on the proximal side from the firstwire and made from a material having an elastic modulus larger than thatof the first wire, and a cover layer provided on the outer periphery ofthe wire body in covering at least the welded portion between the firstwire and the second wire, wherein the welded portion has a projectionprojecting in the outer peripheral direction.

[0011] According to a third aspect of the present invention, there isprovided a guide wire including a wire member including a welded portionformed by welding a first wire disposed on the distal side of the wiremember to a second wire disposed on the proximal side from the firstwire and made from a material having an elastic modulus larger than thatof the first wire, and a cover layer provided on the outer periphery ofthe wire covering at least the welded portion between the first wire andthe second wire, and a distal-side cover layer disposed on the distalside from the cover layer, the distal-side cover layer being made from amaterial different from that of the cover layer.

[0012] In the above guide wire, preferably, the cover layer is formed insuch a manner that the wire body is substantially not heated at the timeof covering the wire body with the cover layer, and the distal-sidecover layer is formed in such a manner that the wire body is heated atthe time of covering the wire body with the distal-side cover layer.

[0013] According to a fourth aspect of the present invention, there isprovided a guide wire including a wire member including a welded portionformed by welding a first wire disposed on the distal side of the wiremember to a second wire disposed on the proximal side from the firstwire and made from a material having an elastic modulus larger than thatof the first wire, and a cover layer provided on the outer periphery ofthe wire body covering at least the welded portion between the firstwire and the second wire, and a proximal-side cover layer disposed onthe proximal side from the cover layer, the proximal-side cover layerbeing made from a material different from that of the cover layer.

[0014] In the above guide wire, preferably, the cover layer is formed insuch a manner that the wire body is substantially not heated at the timeof covering the wire body with the cover layer, and the proximal-sidecover layer is formed in such a manner that the wire body is heated atthe time of covering the wire body with the proximal-side cover layer.

[0015] The distal-side cover layer may be made from a material capableof reducing the friction of the distal-side cover layer. In particular,the distal-side cover layer is preferably made from a fluorocarbon resinor hydrophilic material.

[0016] The average thickness of the distal-side cover layer ispreferably in a range of 1 to 20 μm.

[0017] The proximal-side cover layer may be made from a material capableof reducing the friction of the proximal-side cover layer. Inparticular, the proximal-side cover layer is preferably made from afluorocarbon resin or hydrophilic material.

[0018] The average thickness of the proximal-side cover layer ispreferably in a range of 1 to 20 μm.

[0019] The welded portion preferably has a projection projecting in theouter peripheral direction.

[0020] The second wire preferably has, in the vicinity of the weldedportion, a portion with its cross-sectional area smaller than that of aproximal end portion of the first wire.

[0021] The cover layer may be made from a material capable of reducingthe friction of the cover layer. In particular, the cover layer ispreferably made from a fluorocarbon resin or hydrophilic material.

[0022] The cover layer is preferably made from a silicone resin. Thecover layer preferably functions as a reinforcing layer for reinforcingthe welded portion.

[0023] The cover layer is preferably made from a metal material. Thecover layer is preferably made from a material having rigidity equal toor smaller than that of a material for forming the first wire.

[0024] The average thickness of the cover layer is preferably in a rangeof 1 to 20 μm. The thickness of the cover layer is preferably nearlyuniform.

[0025] The thickness of a portion, which covers at least the weldedportion, of the cover layer is preferably nearly uniform.

[0026] The cover layer is preferably provided in such a manner as tocross the welded portion, and to have a thickness nearly uniform fromthe proximal end to the distal end of the welded portion.

[0027] The cover layer is preferably provided in such a manner as tocross the projection, and to have a thickness nearly uniform from theproximal end to the distal end of the projection.

[0028] The wire body preferably has an outer-diameter gradually reducingportion with its outer diameter gradually reduced in the directiontoward the distal end of the wire body.

[0029] The guide wire preferably has a spiral coil provided so as tocover at least a distal end portion of the first wire. The weldedportion is preferably located on the proximal side from the proximal endof the coil.

[0030] The guide wire preferably has a second cover layer provided so asto cover at least part of the coil.

[0031] The first wire is preferably made from a superelastic alloy. Thesecond wire is preferably made from a stainless steel.

[0032] The second wire is preferably made from a Co-based alloy. TheCo-based alloy is preferably a Co—Ni—Cr alloy.

[0033] A connection end face of the first wire to the second wire and aconnection end face of the second wire to the first wire are preferablyset to be each substantially perpendicular to the axial direction of thefirst and second wires. The welding between the first wire and thesecond wire is preferably performed by a butt resistance weldingprocess.

[0034] The projection is preferably formed at the time of welding thefirst wire and the second wire to each other.

[0035] The guide wire is preferably used in such a manner that thewelded portion is located in a living body.

[0036] As described above, since the guide wire of the present inventionhas the first wire disposed on the distal side and the second wiredisposed on the proximal side from the first wire and made from amaterial having an elastic modulus larger than that of the first wire,it is possible to ensure a high rigidity at a proximal end portion whilekeeping a high flexibility at a distal end portion, and hence to enhancethe pushability, torque transmission performance, and trackability ofthe guide wire.

[0037] Since the first wire and the second wire are joined to each otherby welding, it is possible to enhance the joining strength of thejoining portion (welded portion), and hence to certainly transmit atorsional torque or pushing force from the second wire to the firstwire.

[0038] Since the cover layer is provided on the outer periphery of thewire body in such a manner as to cover at least the welded portion, evenif stepped portions or burrs occur on the outer peripheral surface ofthe welded portion, the stepped portions or burrs can be covered withthe cover layer. As a result, it is possible to prevent or relieve anadverse effect caused by the stepped portions or burrs.

[0039] In the case of providing the cover layer made from a siliconeresin, it is possible to ensure a sufficient sliding performance of theentire guide wire while keeping a high joining strength between thefirst wire and the second wire at the time of forming the cover layer,and hence to enhance the operationality of the guide wire.

[0040] In the case of providing the cover layer made from a materialcapable of reducing the friction of the cover layer, it is possible toimprove the sliding performance of the guide wire in a catheter or thelike, and hence to further enhance the operationality of the guide wire.Since the sliding resistance of the guide wire is reduced, it ispossible to more certainly prevent kink (sharp bending) or torsion ofthe guide wire, particularly, in the vicinity of the welded portion.

[0041] In the case of providing the cover layer functioning as areinforcing layer for reinforcing the welded portion, it is possible tofurther enhance the joining strength between the first wire and thesecond wire. Accordingly, when a torsional torque or pushing force isapplied from the second wire to the first wire, it is possible to morecertainly transmit the torsional torque or pushing force withoutdeformation or breakage of the welded portion.

[0042] In the case of providing the second cover layer, the distal-sidecover layer, and the proximal-side cover layer, which are different fromthe cover layer, it is possible to provide a local portion at which thesliding resistance is larger than that of the cover layer, and hence tofacilitate the placement of the guide wire.

[0043] Since the projection is formed at the welded portion, it ispossible to further enhance the joining strength of the joining portion(welded portion), and hence to more certainly transmit a torsionaltorque or pushing force from the second wire to the first wire.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] These and other objects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription in conjunction with the accompanying drawings, wherein:

[0045]FIG. 1 is a longitudinal sectional view showing a first embodimentof a guide wire of the present invention;

[0046]FIGS. 2A to 2D are views showing steps of a procedure forconnecting a first wire and a second wire of the guide wire shown inFIG. 1;

[0047]FIG. 3 is a longitudinal sectional view showing a secondembodiment of the guide wire of the present invention;

[0048]FIG. 4 is a longitudinal sectional view showing a third embodimentof the guide wire of the present invention;

[0049]FIG. 5 is a longitudinal sectional view showing a fourthembodiment of the guide wire of the present invention;

[0050]FIG. 6 is a longitudinal sectional view showing a modification ofa portion, in the vicinity of a welded portion, of the guide wire of thepresent invention;

[0051]FIG. 7 is a longitudinal sectional view showing anothermodification of the portion, in the vicinity of a welded portion, of theguide wire of the present invention;

[0052]FIG. 8 is a typical view illustrating an example of how to use theguide wire of the present invention; and

[0053]FIG. 9 is a typical view illustrating the example of how to usethe guide wire of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] A guide wire of the present invention will now be described indetail by way of preferred embodiments shown in the accompanyingdrawings.

[0055]FIG. 1 is a longitudinal sectional view of a first embodiment of aguide wire of the present invention, FIGS. 2A to 2D are views showing aprocedure for joining a first wire and a second wire of the guide wireshown in FIG. 1 to each other, and FIG. 3 is a longitudinal sectionalview showing a second embodiment of the guide wire of the presentinvention. For convenience of description, the right side in FIG. 1 andFIGS. 2A to 2D is taken as the “proximal side” and the left side in FIG.1 and FIGS. 2A to 2D is taken as the “distal side”. It is to be notedthat in FIG. 1 and FIGS. 2A to 2D, for easy understanding, the dimensionof the guide wire in the thickness direction is exaggeratedly enlargedwhile the dimension of the guide wire in the length direction isshortened, and therefore, the ratio of the thickness to the length issignificantly different from the actual ratio. The same is true forFIGS. 3 to 5 to be described later.

[0056] A guide wire 1 shown in FIG. 1 is of a type used to be insertedin a catheter, and includes a wire member 10 and a spiral coil 4. Thewire member 10 is formed by joining a first wire 2 disposed on thedistal side to a second wire 3 disposed on the proximal side from thefirst wire 2. The entire length of the guide wire 1 is not particularlylimited but is preferably in a range of about 200 to 5,000 mm. The outerdiameter of a constant outer-diameter portion of the wire member 10 isnot particularly limited but is preferably in a range of about 0.2 to1.2 mm.

[0057] The first wire 2 is configured as a wire having elasticity. Thelength of the first wire 2 is not particularly limited but is preferablyin a range of about 20 to 1,000 mm.

[0058] According to this embodiment, the first wire 2 has anouter-diameter constant portion extending for a specific length from theproximal end, and an outer-diameter gradually reducing portion 15extending from the outer-diameter constant portion to the distal end.The outer-diameter of the outer-diameter gradually reducing portion 15is gradually reduced in the direction toward the distal end. Theprovision of the outer-diameter gradually reducing portion 15 iseffective to gradually reduce the rigidity (flexural rigidity, torsionalrigidity) of the first wire 2 in the direction toward the distal end. Asa result, the distal end portion of the guide wire 1 has a highflexibility, to improve trackability and safety to a blood vessel and toprevent sharp-bending and the like.

[0059] In the configuration shown in the figure, the outer-diametergradually reducing portion 15 is formed as part of the first wire 2;however, such a portion 15 may be formed as the whole of the first wire2. The taper angle (reduction ratio of the outer-diameter) of theouter-diameter gradually reducing portion 15 may be constant orpartially changed in the longitudinal direction of the first wire 2. Forexample, portions in each of which the taper angle (reduction ratio ofthe outer diameter) is relatively large and portions in each of whichthe taper angle is relatively small may be alternately repeated by aplurality of numbers.

[0060] The first wire 2 may be configured such that a portion with itsouter diameter is kept constant in the longitudinal direction be locatedat a middle portion of the outer-diameter gradually reducing portion 15or on the distal side from the outer-diameter gradually reducing portion15. For example, the first wire 2 may be configured such that aplurality of taper portions in each of which the outer diameter isgradually reduced in the direction toward the distal end be formed inthe longitudinal direction and a portion in which the outer diameter iskept constant in the longitudinal direction be formed between adjacenttwo of the taper portions. The first wire 2 having such a configurationcan exhibit the same effect as that described above.

[0061] Unlike the configuration shown in the figure, the proximal end ofthe outer-diameter gradually reducing portion 15 may be located at amiddle point of the second wire 3, and more specifically, theouter-diameter gradually reducing portion 15 may be formed so as tocross the boundary (welded portion 14 to be described later) between thefirst wire 2 and the second wire 3.

[0062] The material for forming the first wire 2 is not particularlylimited but may be selected from metal materials such as stainlesssteels. In particular, alloys having pseudo-elasticity (for example,superelastic alloys) are preferable, and superelastic alloys are morepreferable. Superelastic alloys are relatively flexible, good inrestoring performance, and less susceptible to reforming. Accordingly,if the first wire 2 is made from a superelastic alloy, the guide wire 1including such a first wire 2 has, at its distal portion, a highflexibility and a high restoring performance against bending, and a hightrackability to a blood vessel complicatedly curved or bent, to therebyenhance the operationality of the guide wire 1. Even if the first wire 2is repeatedly deformed, that is, curved or bent, the first wire 2 is noor less plastic deforming because of its high restoring performance.This prevents degradation of the operationality due to the plasticdeforming of the first wire 2 during use of the guide wire 1.

[0063] Pseudo-elastic alloys include those of a type in which thestress-strain curve in a tensile test has any shape, those of a type inwhich a transformation point such as As, Af, Ms, or Mf can besignificantly measured or not measured, and those of all types in whichthe shape is greatly deformed by stress and then restored nearly to anoriginal shape by removal of stress.

[0064] Examples of superelastic alloys include Ni—Ti alloys such as anNi—Ti alloy containing Ni in an amount of 49-52 atomic %, a Cu—Zn alloycontaining Zn in an amount of 38.5 to 41.5 wt %, a Cu—Zn—X alloycontaining X in an amount of 1 to 10 wt % (X: at least one kind selectedfrom a group consisting of Be, Si, Sn, Al, and Ga), and an Ni—Al alloycontaining Al in an amount of 36 to 38 atomic %. Of these materials, theNi—Ti alloy is preferable. In addition, a superelastic alloy representedby a Ni—Ti alloy is excellent in adhesion against a cover layer 5 or asecond cover layer 6.

[0065] The distal end of the second wire 3 is joined to the proximal endof the first wire 2 at a welded portion 14 by welding. The second wire 3is a wire member having elasticity. The length of the second wire 3 isnot particularly limited but may be in a range of about 20 to 4,800 mm.

[0066] The second wire 3 is made from a material having an elasticmodulus (Young's modulus or modulus of longitudinal elasticity, modulusof rigidity or modulus of transverse elasticity, or bulk modulus) largerthan that of the first wire 2. The second wire 3 can thus exhibit anappropriate rigidity (flexural rigidity, torsional rigidity). As aresult, the guide wire 1 becomes firm, to improve the pushability andtorque transmission performance, thereby enhancing the operationality atthe time of insertion of the guide wire 1.

[0067] The material for forming the second wire 3 is not particularlylimited but may be selected from metal materials, for example, stainlesssteels (all kinds specified in SUS, for example, SUS304, SUS303, SUS316,SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429,SUS430F, and SUS302), piano wire steels, cobalt alloys, and alloyshaving pseudo-elasticity.

[0068] In particular, cobalt alloys are preferably used for the secondwire 3. This is because the second wire 3 made from a cobalt alloy has ahigh elastic modulus and an appropriate elastic limit. Such a secondwire 3 exhibits a good torque transmission performance, thereby hardlycausing a problem associated with buckling or the like. Any type ofcobalt alloy may be used insofar as it contains cobalt. In particular, acobalt alloy containing cobalt as a main component (that is, acobalt-based alloy containing cobalt in an amount [in wt %] being thelargest among the contents of all components of the alloy) is preferablyused, and further, a Co—Ni—Cr alloy is more preferable. The use of thecobalt alloy having such a composition as the material for forming thesecond wire 3 is effective to further enhance the above-describedeffects. The cobalt alloy having such a composition is also advantageousin that since the alloy exhibits plasticity in deformation at roomtemperature, the second wire 3 made from such a cobalt alloy is easilydeformable into a desired shape, for example, during use of the guidewire. A further advantage of the cobalt alloy having such a compositionis as follows: namely, since the second wire 3 made from such a cobaltalloy has a high elastic modulus and is cold-formable even if itexhibits a high elastic limit, the second wire 3 can be thinned whilesufficiently preventing occurrence of buckling, and therefore, canexhibit a high flexibility and a high rigidity enough to be insertedinto a desired site.

[0069] The Co—Ni—Cr alloy is exemplified by an alloy containing 28-50 wt% of Co, 10-30 wt % of Ni, and 10-30 wt % of Cr, the balance being Fe.In this alloy, part of any component may be substituted by anotherelement (substitution element). The incorporation of such a substitutionelement exhibits an effect inherent to the kind thereof. For example,the incorporation of at least one kind selected from a group consistingof Ti, Nb, Ta, Be, and Mo further improves the strength of the secondwire 3. In the case of incorporating one or more substitution elementsother than Co, Ni, and Cr, the total content of the substitutionelements is preferably in a range of 30 wt % or less.

[0070] For example, part of Ni may be substituted by Mn, which iseffective to further improve the workability. Part of Cr may besubstituted by Mo and/or W, which is effective to further improve theelastic limit. Of the Co—Ni—Cr alloys, a Co—Ni—Cr—Mo alloy isparticularly preferable.

[0071] Examples of compositions of the Co—Ni—Cr alloys include (1) 40 wt% Co—22 wt % Ni—25 wt % Cr—2 wt % Mn—0.17 wt % C—0.03 wt % Be—Fe(balance), (2) 40 wt % Co—15 wt % Ni—20 wt % Cr—2 wt % Mn—7 wt % Mo—0.15wt % C—0.03 wt % Be—Fe (balance), (3) 42 wt % Co—13 wt % Ni—20 wt %Cr—1.6 wt % Mn—2 wt % Mo—2.8 wt % W—0.2 wt % C—0.04 wt % Be—Fe(balance), (4) 45 wt % Co—21 wt % Ni—18 wt % Cr—1 wt % Mn—4 wt % Mo—1 wt% Ti—0.02 wt % C—0.3 wt % Be—Fe (balance), and (5) 34 wt % Co—21 wt %Ni—14 wt % Cr—0.5 wt % Mn—6 wt % Mo—2.5 wt % Nb—0.5 wt % Ta—Fe(balance). The wording “Co—Ni—Cr alloy” used herein is the conceptionincluding these Co—Ni—Cr alloys.

[0072] If a stainless steel is used as the material for forming thesecond wire 3, the pushability and torque transmission performance canbe further enhanced.

[0073] The first wire 2 and the second wire 3 may be made from differentalloys, and particularly, the first wire 2 is preferably made from amaterial having an elastic modulus smaller than that of the material ofthe second wire 3. With this configuration, the distal end portion ofthe guide wire 1 has a high flexibility, and the proximal end portion ofthe guide wire 1 has a high rigidity (flexural rigidity, torsionalrigidity). As a result, the guide wire 1 has a high pushability and ahigh torque transmission performance, thereby enhancing theoperationality, and also exhibits, on the distal side, a highflexibility and a high restoring performance, thereby improvingtrackability and safety to a blood vessel.

[0074] As one preferred combination of materials of the first wire 2 andthe second wire 3, the first wire 2 is made from a superelastic alloyand the second wire 3 is made from a Co—Ni—Cr alloy or a stainlesssteel. With this configuration, the above-described effects become moresignificant.

[0075] In the configuration shown FIG. 1, the second wire 3 has a nearlyconstant outer diameter over the entire length; however, the second wire3 may have portions with outer diameters changed in the longitudinaldirection.

[0076] From the viewpoint of enhancing the flexibility and restoringperformance of the distal end portion of the first wire 2, it ispreferred to use a Ni—Ti alloy as the superelastic alloy for forming thefirst wire 2.

[0077] The coil 4 is a member formed by spirally winding a wire,especially fine filamentous wire, and is provided so as to cover thedistal end portion of the first wire 2. In the configuration shown inFIG. 1, the distal end portion of the first wire 2 is disposed in anapproximately axially center portion of the coil 4 in such a manner asto be not in contact with the inner surface of the coil 4. In addition,the welded portion 4 is located on the proximal side from the proximalend of the coil 4.

[0078] It is to be noted that in the configuration shown in FIG. 1, thecoil 4 is loosely disposed in such a manner that a slight gap remainsbetween adjacent spirally wound wire portions in a state that noexternal force is applied to the coil 4; however, the coil 4 may betightly disposed in such a manner that no gap remains between theadjacent spirally wound wire portions in a state that no external forceis applied to the coil 4.

[0079] The coil 4 may be made from a metal material such as a stainlesssteel, a superelastic alloy, a cobalt alloy, a noble metal such as gold,platinum, or tungsten, or an alloy containing such a noble metal. Inparticular, the coil 4 is preferably made from a radiopaque materialsuch as a noble metal. If the coil 4 is made from such a radiopaquematerial, the guide wire 1 can exhibit an X-ray contrast performance.This makes it possible to insert the guide wire 1 in a living body whileconfirming the position of the distal end portion of the guide wire 1under fluoroscopy. The distal side and proximal side of the coil 4 maybe made from different alloys. For example, the distal side of the coil4 may be formed of a coil made from a radiopaque material and theproximal side of the coil 4 be formed of a coil made from a relativelyradiolucent material such as a stainless material. The entire length ofthe coil 4 is not particularly limited but may be in a range of about 5to 500 mm.

[0080] The proximal end portion and the distal end portion of the coil 4are fixed to the first wire 2 by a fixing material 11 and a fixingmaterial 12, respectively, and an intermediate portion (close to thedistal end) of the coil 4 is fixed to the first wire 2 by a fixingmaterial 13. Each of the fixing materials 11, 12, and 13 is a solder(brazing material). Alternatively, each of the fixing materials 11, 12,and 13 may be an adhesive. In addition, in place of using the fixingmaterial, the coil 4 may be fixed to the first wire 2 by welding. Toprevent damage of the inner wall of a blood vessel, the leading endsurface of the fixing material 12 is preferably rounded.

[0081] According to this embodiment, since the first wire 2 is partiallycovered with the coil 4, the contact area of the first wire 2 with theinner wall of a catheter used together with the guide wire 1 is small,with a result that it is possible to reduce the sliding resistance ofthe guide wire 1 in the catheter. This is effective to further improvethe operationality of the guide wire 1.

[0082] In this embodiment, the wire having a circular shape incross-section is used for the coil 4; however, the cross-sectional shapeof the wire used for the coil 4 may be another shape such as an ellipticshape or a quadrilateral shape (especially, rectangular shape).

[0083] In the guide wire 1, the first wire 2 and the second wire 2 arejoined to each other by welding. The welded portion (joining portion) 14between the first wire 2 and the second wire 3 has a high joiningstrength, to allow a torsional torque or pushing force to be certainlytransmitted from the second wire 3 to the first wire 2.

[0084] The outer peripheral portion of the welded portion 14 ispreferably made substantially smooth, for example, in accordance withsteps 3 and 4 of a procedure of joining the first wire 1 to the secondwire 2 by welding (to be described later).

[0085] In this embodiment, a connection end face 21 of the first wire 2to the second wire 3 and a connection end face 31 of the second wire 3to the first wire 2 are each formed into a plane nearly perpendicular tothe axial (longitudinal) direction of both the wires 2 and 3. Thissignificantly facilitates working for forming the connection end faces21 and 31, to achieve the above-described effects without complicatingthe steps for producing the guide wire 1.

[0086] It is to be noted that each of the connection end faces 21 and 31may be tilted relative to the plane perpendicular to the axial(longitudinal) direction of both the wires 2 and 3, or formed into arecessed or raised shape.

[0087] The method of welding the first wire 2 and the second wire 3 toeach other is not particularly limited but is generally exemplified byspot welding using laser or butt resistance welding such as butt seamwelding. In particular, to ensure a high joining strength of the weldedportion 14, butt resistance welding is preferable.

[0088] The procedure of joining the first wire 2 and the second wire 3to each other by butt seam welding as one example of butt resistancewelding will be described with reference to FIGS. 2A to 2D. FIGS. 2A to2D show steps 1 to 4 of the procedure of joining the first wire 2 andthe second wire 3 to each other by butt seam welding.

[0089] In the step 1, the first wire 2 and the second wire 3 are fixed(mounted) to a butt welder (not shown).

[0090] In the step 2, the connection end face 21 on the proximal side ofthe first wire 2 and the connection end face 31 on the distal side ofthe second wire 3 are butted to each other while a specific voltage isapplied thereto by the butt welder. With this operation, a fused layer(welded surface) is formed at the contact portion, whereby the firstwire 2 and the second wire 3 are strongly joined to each other.

[0091] In the step 3, a projection of the joining portion (weldedportion 14), formed by deformation of the joining portion upon buttwelding, is removed, with a result that the outer periphery of thewelded portion 14 is made substantially smooth. The removal of theprojection may be performed by polishing, grinding, or chemicaltreatment such as etching.

[0092] In the step 4, a portion, on the distal side from the joiningportion (welded portion 14), of the first wire 2 is polished or ground,to form the outer-diameter gradually reducing portion 15 with its outerdiameter gradually reduced in the direction toward the distal end.

[0093] If the proximal end of the outer-diameter gradually reducingportion 15 is set on the proximal side from the welded portion 14, theprocedure may be jumped from the step 2 to the step 4, with the step 3omitted.

[0094] The wire member 10 has a cover layer 5 that covers the whole orpart of the outer surface (outer peripheral surface). The cover layer 5can be formed for satisfying various purposes, one of which is to reducethe friction (sliding resistance) of the guide wire 1 for improving thesliding performance of the guide wire 1, thereby enhancing theoperationality of the guide wire 1.

[0095] To satisfy the above-described purpose, the cover layer 5 ispreferably made from a material capable of reducing the friction of theguide wire 1. With this configuration, since the friction resistance(sliding resistance) of the guide wire 1 against the inner wall of acatheter used together with the guide wire 1 is reduced, the slidingperformance of the guide wire 1 is improved, to enhance theoperationality of the guide wire 1 in the catheter. Further, since thesliding resistance of the guide wire 1 is reduced, it is possible tomore certainly prevent, at the time of movement and/or rotation of theguide wire 1 in the catheter, kink (sharp bending) or torsion of theguide wire 1, particularly, in the vicinity of a welded portion of theguide wire 1.

[0096] Examples of the materials capable of reducing the friction of theguide wire 1 include polyorefins such as polyethylene and polypropylene,polyvinyl chloride, polyesters (such as PET and PBT), polyamide,polyimide, polyurethane, polystyrene, polycarbonate, silicone resins,fluorocarbon resins (such as PTFE and ETFE), and composite materialsthereof.

[0097] In particular, the use of a fluorocarbon resin or a compositematerial thereof as the material for forming the cover layer 5 isadvantageous in effectively reducing the friction resistance (slidingresistance) of the guide wire 1 having such a cover layer 5 against theinner wall of a catheter, to improve the sliding performance, therebyenhancing the operationality of the guide wire 1 in the catheter.Further, in the case of moving and/or rotating the guide wire 1 havingsuch a cover layer 5 in the catheter, it is possible to more certainlyprevent kink (sharp bending) or torsion of the guide wire, particularly,in the vicinity of the welded portion 14.

[0098] The formation of the cover layer 5 using a fluorocarbon resin ora composite material thereof is generally performed by heating thefluorocarbon resin and covering the wire member 10 with the fluorocarbonresin, for example, in accordance with a baking process or sprayingprocess. Such a covering process is effective to significantly enhancethe adhesion of the cover layer 5 with the wire member 10.

[0099] In the case of using a silicone resin or a composite materialthereof as the material for forming the cover layer 5, it is possible toform the cover layer 5 certainly, strongly adhering on the wire member10 without the need of heating the silicone resin. To be more specific,by using a silicone resin of a reaction-curing type or a compositematerial thereof, the formation of the cover layer 5 can be performed atroom temperature. The formation of the cover layer 5 at room temperatureis advantageous not only in realizing simple coating but alsosufficiently keeping the joining strength of the welded portion 14between the first wire 2 and the second wire 3 without thermaldegradation of the welded portion 14.

[0100] A hydrophilic material or a hydrophobic material can be also usedas another preferred example of the material capable of reducing thefriction of the guide wire 1. In particular, the hydrophilic material ispreferable.

[0101] Examples of the hydrophilic materials include a cellulose basedpolymer, a polyethylene oxide based polymer, a maleic anhydride basedpolymer (for example, a maleic anhydride copolymer such asmethylvinylether-maleic anhydride copolymer), an acrylic amide basedpolymer (for example, polyacrylic amide or polyglycidylmethacrylate-dimethyl acrylic amide [PGMA-DMAA] block copolymer),water-soluble nylon, polyvinyl alcohol, and polyvinyl pyrolidone.

[0102] In many cases, the hydrophilic material can exhibit a lubricatingperformance in a wet (water-absorbing) state. The use of the covermember 5 made from such a hydrophilic material is effective to reducethe friction resistance (sliding resistance) of the guide wire 1 againstthe inner wall of a catheter used together with the guide wire 1, toimprove the sliding performance of the guide wire 1, thereby enhancingthe operationality of the guide wire 1 in the catheter.

[0103] The cover layer 5 may be formed in such a manner as to cover thewhole or part of the wire member 10 in the longitudinal direction. Inparticular, the cover layer 5 is preferably formed so as to cover thewelded portion 14, and specifically, formed in a region including thewelded portion 14. With this configuration, even if stepped portions orburrs may occur on the outer peripheral portion of the welded portion14, such stepped portions or burrs are covered with the covered layer 5,whereby a sufficient sliding performance can be ensured. Also, since thecover layer 5 has a nearly uniform outer diameter, the slidingperformance can be further improved.

[0104] The thickness (in average) of the cover layer 5 is notparticularly limited but is preferably in a range of about 1 to 20 μm,more preferably, about 2 to 10 μm. If the thickness of the cover layer 5is less than the lower limit, the effect obtained by formation of thecover layer 5 may be not sufficiently achieved and the cover layer 5 maybe often peeled. If the thickness of the cover layer 5 is more than theupper limit, the physical properties of the wire may be obstructed andthe cover layer 5 may be often peeled.

[0105] According to the present invention, the outer peripheral surfaceof the wire member 10 may be subjected to a treatment (such as chemicaltreatment or heat treatment) for improving the adhesion characteristicof the cover layer 5, or may be provided with an intermediate layer forimproving the adhesion characteristic of the cover layer 5.

[0106] A second embodiment of the guide wire of the present inventionwill be described with reference to FIG. 3, principally, aboutdifferences from the first embodiment, with the description of the samefeatures omitted.

[0107] A guide wire 1 shown in FIG. 3 is configured such that the distalend of a cover layer 5 is located on the proximal side from the proximalend of a coil 4, and a second cover layer 6 different from the coverlayer 5 is formed on the distal side from the cover layer 5.

[0108] The second cover layer 6 is provided so as to cover the whole orpart of the coil 4. In the configuration shown in the figure, the secondcover layer 6 covers the whole of the coil 4.

[0109] The second cover layer 6 may be made from a material selectedfrom the above-described materials used for forming the cover layer 5and other materials, for example, polyorefins such as polyethylene andpolypropylene, polyvinyl chloride, polyesters (such as PET and PBT),polyamide, polyimide, polyurethane, polystyrene, polycarbonate,fluorocarbon resins, silicone resins, silicone rubbers, and variouskinds of elastomers (for example, thermoplastic elastomers such aspolyamide-based elastomer and polyester-based elastomer). The materialfor forming the second cover layer 6 may be identical to or differentfrom the material for forming the cover layer 5.

[0110] The materials for forming the cover layer 5 and the second coverlayer 6 are not particularly limited as described above, but arepreferably set such that a silicone resin or a composite material beused for forming the cover layer 5 and a fluorocarbon resin or acomposite material thereof be used for forming the second cover layer 6.

[0111] With this configuration, it is possible to combine theabove-described advantage obtained by the use of a silicone resin withan advantage obtained by the use of a fluorocarbon resin. Concretely, byadopting such a combination of the materials of the cover layer 5 andthe second cover layer 6, it is possible to obtain a sufficient slidingperformance of the entire guide wire 1 while keeping the joiningstrength of the welded portion 14 between the first wire 2 and thesecond wire 3, and hence to enhance the operationality of the guide wire1.

[0112] In the case of using a silicone resin or a composite materialthereof for forming the cover layer 5 and also using a fluorocarbonresin or a composite material for forming the second cover layer 6, itis preferred that the wire member 10 be not heated for forming the coverlayer 5 as described above and be heated for forming the second coverlayer 6. With this configuration, it is possible to make theabove-described effect significant and to enhance the adhesion of thesecond cover layer 6 with the wire member 10.

[0113] In the case of using a hydrophobic resin for forming the coverlayer 5 and also using a hydrophilic resin for forming the second coverlayer 6, it is possible to improve the sliding performance in a catheterand to enhance crossability in a blood vessel.

[0114] The thickness (in average) of the second cover layer 6 is notparticularly limited but is preferably in a range of about 1 to 20 μm,more preferably, about 2 to 10 μm. The thickness of the second coverlayer 6 may be identical to or different from that of the cover layer 5.

[0115] The guide wire of the present invention may be not provided withthe coil 4. In this case, the second cover layer 6 may be provided ornot provided at the position where the coil 4 is omitted.

[0116] In the configuration shown in FIG. 3, the distal end of the coverlayer 5 is joined to the proximal end of the second cover layer 6, andis therefore continuous thereto; however, the distal end of the coverlayer 5 may be separated from the proximal end of the second cover layer6, or the cover layer 5 may be partially overlapped to the second coverlayer 6.

[0117]FIG. 4 is a longitudinal sectional view showing a third embodimentof the guide wire of the present invention. The third embodiment of theguide wire of the present invention will be described with reference toFIG. 4, principally, about differences from the previous embodiments,with the description of the same features omitted.

[0118] According to a guide wire 1 in this embodiment, a first wire 2has an outer-diameter gradually reducing portion 15 and anouter-diameter gradually reducing portion 16 provided on the proximalside from the outer-diameter gradually reducing portion 15. In this way,the first wire 2 (or second wire 3) may have outer-diameter graduallyreducing portions at a plurality of positions.

[0119] According to the guide wire 1 in this embodiment, the second wire3 has an outer-diameter gradually reducing portion 18 in the vicinity ofthe distal end thereof. To be more specific, the second wire 3 has afirst portion provided in the vicinity of the distal end and a secondportion provided on the proximal side from the first portion, whereinthe second portion has rigidity higher than that of the first portion.This gives rise to an effect of making transition of elasticity betweenthe first wire 2 and the second wire 3 smooth.

[0120] In this embodiment, a welded portion 14 has a projection 17projecting in the outer peripheral direction. The formation of such aprojection 17 is effective to enlarge a joining area between the firstwire 2 and the second wire 3, and hence to significantly enhance thejoining strength. This is advantageous in more certainly transmitting atorsional torque or pushing force from the second wire 3 to the firstwire 2.

[0121] The formation of the projection 17 may make the welded portion 14between the first wire 2 and the second wire 3 easily visible underfluoroscopy. As a result, it is possible to easily, certainly recognizethe advancing state of the guide wire 1 and a catheter in a blood vesselor the like by checking the fluoroscopic image, and hence to shorten theoperation time and to improve the safety.

[0122] The height of the projection 17 is not particularly limited butis preferably in a range of 0.001 to 0.3 mm, more preferably, 0.005 to0.05 mm. If the height of the projection 17 is less than the lowerlimit, it may fail to sufficiently obtain the above-described effectsdepending on the materials of the first wire 2 and the second wire 3. Ifthe height of the projection 17 is more than the upper limit, since theinner diameter of a lumen, in which the guide wire 1 is to be inserted,of a balloon catheter is fixed, the outer diameter of the. second wire 3on the proximal side must be thin relative to the height of theprojection 17, with a result that it may become difficult to ensuresufficient physical properties of the second wire 3.

[0123] The projection 17 can be formed by smoothly shaping theprojection in the step 3 of the above-described procedure of joining thefirst wire 2 to the second wire 3 (see FIG. 2). In particular, in thecase where the second wire 2 has the outer-diameter gradually reducingportion (small cross-sectional area portion) 18 as in the guide wire 1according to this embodiment, the projection 17 can be formed by weldingthe first wire 2 to the second wire 3 having a cross-sectional areagradually reducing (small cross-sectional area portion) with itscross-sectional area gradually reduced in the direction toward thedistal end by the above-described procedure.

[0124] A cover layer 5 covers the outer-diameter gradually reducingportion 18 and the projection 17 and has a substantially uniform outerdiameter. The term “substantially uniform outer diameter” contains anouter diameter smoothly changed within such a range as not to cause anyinconvenience in use of the guide wire.

[0125] In this embodiment, the cover layer 5 covers a region includingthe coil 4, the first wire 2, and the second wire 3; however, the coverlayer 5 may be formed so as to cover the first wire 2 and the secondwire 3, and the coil 4 be covered with a material different from thecover layer 5, for example, a hydrophilic material.

[0126]FIG. 5 is a longitudinal sectional view showing a fourthembodiment of the guide wire of the present invention. The fourthembodiment of the guide wire of the present invention will be describedwith reference to FIG. 5, principally, about differences from theprevious embodiments, with the description of the same features omitted.

[0127] According to a guide wire 1 in this embodiment, a cover layer 5is formed so as to cover the vicinity of a welded portion 14 of a wiremember 10, a distal-side cover layer 6′ different from the cover layer 5is formed on the distal side from the cover layer 5, and a proximal-sidecover layer 7 different from the cover layer 5 is formed on the proximalside from the cover layer 5.

[0128] The distal-side cover layer 6′ may be made from a materialselected from the materials used for forming the cover layer 5 and thesecond cover layer 6 in the previous embodiments. The material forforming the distal-side cover layer 6′ may be identical to or differentfrom that of each of the cover layer 5 and the proximal-side cover layer7.

[0129] The material of the proximal-side cover layer 7 is notparticularly limited but may be selected from the materials used forforming the cover layer 5 and the distal-side cover layer 6′ and othermaterials. The material of the proximal-side cover layer 7 may beidentical to or different from the material used for forming each of thecover layer 5 and the distal-side cover layer 6′.

[0130] The proximal-side cover layer 7 may be made from any material asdescribed above, but is preferably made from a fluorocarbon resin or acomposite material thereof. This makes it possible to effectively reducethe friction resistance (sliding resistance) of the guide wire 1 againstthe inner wall of a catheter and improve the sliding performance, andhence to enhance the operationality of the guide wire 1 in the catheter.Further, in the case of moving and/or rotating the guide wire 1 in thecatheter, it is possible to more certainly prevent kink (sharp bending)or torsion of the guide wire 1, particularly, in the vicinity of thewelded portion.

[0131] The materials of the cover layer 5, the distal-side cover layer6′, and the proximal-side cover layer 7 are preferably set such that thecover layer 5 be made from a silicone resin or a composite materialthereof, the distal-side cover layer 6′ be made from a fluorocarbonresin or a composite material thereof, and the proximal-side cover layer7 be made from a fluorocarbon resin or a composite material thereof.

[0132] With this configuration, it is possible to combine theabove-described advantage obtained by the use of a silicone resin withthe above-described advantage obtained by the use of a fluorocarbonresin. Concretely, by adopting such a combination of the materials ofthe cover layer 5, the distal-side cover layer 6′, and the proximal-sidecover layer 7, it is possible to obtain a sufficient sliding performanceof the entire guide wire 1 while keeping the joining strength of thewelded portion 14 between the first wire 2 and the second wire 3, andhence to enhance the operationality of the guide wire 1.

[0133] In the case of using the above-described combination of thematerials for forming the cover layer 5, the distal-side cover layer 6′,and the proximal-side cover layer 7, as described above, it is preferredthat the wire member 10 be not heated for forming the cover layer 5 andbe heated for forming each of the distal-side cover layer 6′ and theproximal-side cover layer 7. With this configuration, it is possible tomake the above-described effect significant and to enhance the adhesionof each of the distal-side cover layer 6′ and the proximal-side coverlayer 7 on the wire member 10.

[0134] The thickness (in average) of the distal-side cover layer 6′ isnot particularly limited but is preferably in a range of about 1 to 20μm, more preferably, about 2 to 10 μm. The thickness of the distal-sidecover layer 6′ may be identical to or different from each of thethickness of the cover layer 5 and the thickness of the proximal-sidecover layer 7.

[0135] The thickness (in average) of the proximal-side cover layer 7 isnot particularly limited but is preferably in a range of about 1 to 20μm, more preferably, about 2 to 10 μm. The thickness of theproximal-side cover layer 7 may be identical to or different from eachof the thickness of the cover layer 5 and the thickness of thedistal-side cover layer 6′.

[0136] In the configuration shown in FIG. 5, the proximal end of thecover layer 5 is joined to the distal end of the proximal-side coverlayer 7, and is therefore continuous thereto; the proximal end of thecover layer 5 may be separated from the distal end of the proximal-sidecover layer 7, or the cover layer 5 may be partially overlapped to theproximal-side cover layer 7.

[0137] In this embodiment, the distal-side cover layer 6′ covers thecoil 4; however, the coil 4 may be covered with a different material,for example, a hydrophilic material.

[0138]FIGS. 6 and 7 are longitudinal sectional views showingmodifications of a portion, in the vicinity of the welded portion, ofthe guide wire of the present invention.

[0139] As shown in FIG. 6, a cover layer 5′ is formed on the outerperiphery of a portion, in the vicinity of a welded portion 14, of awire member 10 in such a manner as to cover the outer periphery of thewelded portion 14, that is, to cross the welded portion 14. Like theabove-described configuration, a distal-side cover layer 6′ and aproximal-side cover layer 7 are formed on the distal side and theproximal side from the cover layer 5′, respectively. In this case, thethickness of the cover layer 5′ is nearly uniform in the axialdirection.

[0140] The cover layer 5′ functions as a reinforcing layer forreinforcing the welded portion 14. The provision of such a cover layer5′ is effective to improve the welding strength of the welded portion14. As a result, in the case of applying a torsional torque or a pushingforce from the second wire 3 to the first wire 2, it is possible toprevent deformation and breakage of the welded portion 14, and hence tomore certainly transmit the torsional torque or pushing force.

[0141] The cover layer 5′ may be made from a material selected frommetal materials and resin materials. In particular, a metal material ispreferably used.

[0142] The cover layer 5′ is preferably made from a material having arigidity equal to or smaller than that of the above-described materialfor forming the first wire 2, that is, having a flexibility equal to orlarger than that of the material for forming the first wire 2. With thisconfiguration, it is possible to obtain the advantage by theabove-described reinforcing effect while sufficiently ensuring theflexibility and restoring performance against bending in the vicinity ofthe welded portion 14.

[0143] A projection 17 projecting in the outer peripheral direction isformed on a welded portion 14 shown in FIG. 7. The effect obtained byformation of the projection 17, and the condition and forming method ofthe projection 17 may be the same as those described above.

[0144] A cover layer 5 similar to that described above is provided onthe outer periphery of a wire member 10. In this case, the cover layer 5is formed so as to cross the projection 17, that is, cross the weldedportion 14. The thickness of the cover layer 5 is nearly uniform fromthe proximal end to the distal end of the projection 17. With thisconfiguration, it is possible to sufficiently ensure the flexibility andrestoring performance against bending in the vicinity of the weldedportion 14.

[0145] In the configuration shown in FIGS. 4, 5, and 7, each of one side(upper side in the figure) and the other side (lower side in the figure)of the projection 17 is formed into an approximately circular-arc shapein longitudinal cross-section, and the welded portion 14 is located onthe maximum outer-diameter portion of the projection 17. This isadvantageous in enlarging an area of the welded surface of the weldedportion 14, thereby obtaining a higher joining strength (weldingstrength).

[0146] According to the present invention, the shape of the projection17 and the position of the welded portion 14 relative to the projection17 are not limited to those described above. For example, each of oneside and the other side of the projection 17 may be formed into anon-circular (non-circular arc) such as a trapezoidal or triangularshape in longitudinal cross-section. The proximal side and the distalside of the projection 17 may be formed into shapes asymmetric to eachother with respect to the welded surface (connection end face 21, 31) ofthe welded portion 14. The axial position of the welded surface of thewelded portion 14 relative to the projection 17 is not necessarilylocated at the central portion as shown in FIGS. 4, 5, and 7 but may belocated at a position offset to the proximal side (second wire 3 side)or on the distal side (first wire 2 side). With this configuration, itis possible to prevent or relieve stress concentration at the weldedportion 14, and hence to more certainly prevent breakage of the weldedportion 14 due to stress concentration at the welded portion 14 when atorsional torque or pushing force is applied from the second wire 3 tothe first wire 2.

[0147] The cover layer 5 covering the projection 17 may be configured asthe reinforcing layer described in the embodiment shown in FIG. 6. Inthe case of covering the projection 17 with a metal material, thejoining strength of the projection 17 can be improved. For example, byinserting a relatively thin metal tube to a portion near the projection17 and applying a pressure to the metal tube from external, the coverlayer 5 strongly adhering on the projection 17 can be formed.

[0148]FIGS. 8 and 9 are views showing the operational state of the guidewire 1 of the present invention during use in the PTCA process.

[0149] In FIGS. 8 and 9, reference numeral 40 denotes an aortic arch, 50is a right coronary artery of a heart, 60 is an ostium of the rightcoronary artery 50, and 70 is a target angiostenosis portion. Further,reference numeral 30 denotes a guiding catheter for certainly guidingthe guide wire 1 from an arteria fermoralis into the right coronaryartery 50, and 20 is a balloon catheter having at its distal end anexpandable and contractible balloon 201 for dilating the targetangiostenosis portion 70.

[0150] As shown in FIG. 8, the guide wire 1 is moved in such a mannerthat the distal end thereof projecting from the distal end of theguiding catheter 30 is inserted in the right coronary artery 50 throughthe ostium 60 of the right coronary artery 50. The guide wire 1 isfurther advanced, and is stopped when the distal end thereof passes thetarget angiostenosis portion 70 in the right coronary artery 50. In thisstate, an advance path of the balloon catheter 20 is ensured. At thistime, the welded portion 14 of the guide wire 1 is located in the livingbody, more specifically, in the vicinity of the distal portion of theaortic arch 40.

[0151] As shown in FIG. 9, the balloon catheter 20 is inserted aroundthe guide wire 1 from the proximal side of the guide wire 1. The ballooncatheter 20 is then advanced in such a manner that the distal endthereof projects from the distal end of the guiding catheter 30, goesahead along the guide wire 1, and enters the right coronary artery 50from the ostium 60 of the right coronary artery 50. The balloon catheter20 is stopped when the balloon 201 reaches a position corresponding tothat of the target angiostenosis portion 70.

[0152] A fluid for inflating the balloon 201 is injected in the ballooncatheter 20 from the proximal side of the balloon catheter 20, toinflate the balloon 201, thereby dilating the target angiostenosisportion 70. As a result, deposits such as cholesterol adhering on thearterial wall of the target angiostenosis portion 70 are physicallycompressed against the arterial wall, to eliminate blocking of bloodflow.

[0153] In the above-described embodiments, each of the composingelements of the guide wire may be replaced with a composing elementhaving any other configuration exhibiting the similar effect, and may beprovided with any other additional element.

[0154] While the preferred embodiments of the present invention havebeen described using specific terms, such description is forillustrative purposes only, and it is to be understood that changes andvariations may be made without departing from the spirit or scope of thefollowing claims.

[0155] The entire disclosure of Japanese Patent Application No.2002-232162 filed on Aug. 8, 2002, Japanese Patent Application No.2002-355909 filed on Dec. 6, 2002 and Japanese Patent Application No.2003-156012 filed on May 30, 2003 including specification, claims,drawings, and summary are incorporated herein by reference in itsentirety.

What is claimed is:
 1. A guide wire comprising: a wire member includinga welded portion formed by welding a first wire disposed on the distalside of said wire member to a second wire disposed on the proximal sidefrom said first wire and made from a material having an elastic moduluslarger than that of said first wire, said welded portion being madesubstantially smooth; and a cover layer provided on the outer peripheryof said wire member covering at least said welded portion between saidfirst wire and said second wire.
 2. A guide wire comprising: a wiremember including a welded portion formed by welding a first wiredisposed on the distal side of said wire member to a second wiredisposed on the proximal side from said first wire and made from amaterial having an elastic modulus larger than that of said first wire;and a cover layer provided on the outer periphery of said wire membercovering at least said welded portion between said first wire and saidsecond wire; wherein said welded portion has a projection projecting inthe outer peripheral direction.
 3. A guide wire comprising: a wiremember including a welded portion formed by welding a first wiredisposed on the distal side of said wire member to a second wiredisposed on the proximal side from said first wire and made from amaterial having an elastic modulus larger than that of said first wire;and a cover layer provided on the outer periphery of said wire membercovering at least said welded portion between said first wire and saidsecond wire; and a distal-side cover layer disposed on the distal sidefrom said cover layer, said distal-side cover layer being made from amaterial different from that of said cover layer.
 4. A guide wireaccording to claim 3, wherein said cover layer is formed in such amanner that said wire member is substantially not heated at the time ofcovering said wire member with said cover layer, and said distal-sidecover layer is formed in such a manner that said wire member is heatedat the time of covering said wire member with said distal-side coverlayer.
 5. A guide wire comprising: a wire member including a weldedportion formed by welding a first wire disposed on the distal side ofsaid wire member to a second wire disposed on the proximal side fromsaid first wire and made from a material having an elastic moduluslarger than that of said first wire; and a cover layer provided on theouter periphery of said wire member covering at least said weldedportion between said first wire and said second wire; and aproximal-side cover layer disposed on the proximal side from said coverlayer, said proximal-side cover layer being made from a materialdifferent from that of said cover layer.
 6. A guide wire according toclaim 5, wherein said cover layer is formed in such a manner that saidwire member is substantially not heated at the time of covering saidwire member with said cover layer, and said proximal-side cover layer isformed in such a manner that said wire member is heated at the time ofcovering said wire member with said proximal-side cover layer.